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<p>The membership and communication services have been abstracted
via a set of classes and a factory.  This document is an introduction
to the organization of these classes.</p>

<p>At the lowest level is a <em>NetMember</em>.  A <em>NetMember</em> is a
low-level system-independent notion of a network member.  At this writing,
there is only one implementation, <em>GMSMember</em>.

<p><em>NetMember</em> is intended to be implemented in the service
provider interface but not necessarily exported to the rest of the system.
In the current design, <em>DistributedMember</em> is the type used to
identify peers in the network.

<p>The starting point for accessing membership services is via
<em>MemberFactory</em>.  This class allows one to create a
<em>NetMember</em> using various arguments or a
<em>MembershipManager</em>, which handles most membership services.</p>

<p><em>MemberFactory</em> uses pluggable instances that implement
the service provider interface <em>MemberServices</em>.  At this
writing, there is only one implementation, <em>GMSMemberFactory</em>.</p>

<p>A <em>MembershipManager</em> is the central focus for membership
activity.  It includes startup and shutdown methods, requests for the
current view of members, and a method to send messages.</p>

<p>The current membership view in the system is via <em>NetView</em>,
which also includes a <em>NetViewId</em>, a sequential identifier
that abstracts the <em>ViewId</em> notion from JavaGroups.</p>

<p>One of the arguments to the constructor for a <em>MembershipManager</em>
is a <em>DistributedMembershipListener</em>.  This listener interface
handles membership events, such as new member arrival, member departure,
and message receipt.</p>


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